The Third Punic War was started by Rome out of paranoia of Carthage, which went to massive levels. A reduced power that was a shadow of it's former self and willing to do anything to prevent Roman invasion (except for destroying their city and building a new one inland)... However, the Romans invaded the city and destroyed it.
Now, what if the Romans had made it clear in the post-Second Punic War treaty that it was to be permanent (rather than expiring when the debt was paid as Carthage assumed), or accepted one of the attempts by Carthage to make peace? How long could the rump Carthage be independent? What would be the effects of a subordinate Carthage rather than a Province of Africa in the lead-up to the Roman Epire?
Now, what if the Romans had made it clear in the post-Second Punic War treaty that it was to be permanent (rather than expiring when the debt was paid as Carthage assumed), or accepted one of the attempts by Carthage to make peace? How long could the rump Carthage be independent? What would be the effects of a subordinate Carthage rather than a Province of Africa in the lead-up to the Roman Epire?